1. Field of the Invention
The present invention relates to an alpine ski boot comprising a rigid shell base having a sole, and an upper. The upper is at least partially journalled around a transverse axis on the shell base and its angular position with respect to the transverse axis is controlled by means of an elastic element.
2. Description of Background and Relevant Materials
Different devices have been proposed to assure the optimum maintenance of the foot of the skier in a ski boot, as well as a satisfactory elastic control of the amplitude of displacement of the flexion of the upper of the boot. Satisfactory elastic control of the flexion permits the skier to satisfactorily transmit control forces to the skis.
Thus, for example, French Pat. No. 2 096 248 describes a boot whose flexion of the journalled upper on the shell base is controlled by means of a spring apparatus mounted obliquely between the front of the upper and the top of the shell base in the median axis of the boot. This apparatus acts in the manner of a suspension to generate elastic resistance opposing the frontward inclination (or flexion) of the upper, beginning at a predetermined position of the upper, resting on the shell base. As soon as the flexional forces pivoting the boot frontwardly cease, the apparatus pushes the upper back to its initial position.
According to another apparatus such as is taught in French Pat. No. 2 103 171, the flexion control apparatus is positioned on the lateral portions of the boot and extends between the shell base and the lower front portion of the upper.
In the devices cited above, the flexion control apparatus projects onto the boot by virtue of the use of elastic elements such as compression springs which necessitate the use of a guidance means and a relatively large housing for optimum functioning. Furthermore, the use of such springs is not entirely satisfactory, particularly because they oppose the flexional forces by generating an initial elastic resistance opposing flexion of the boot which is relatively weak compared to the elastic resistance to flexion at the end of the flexion. This provides unsatisfactory control of the skis when the boot is slightly flexed.
Other ski boots have been developed whose flexion control apparatus is integrated into the normal volume encompassed by boot. This type of boot is described in French Patent Application No. 2 484 800. In this boot the elastic element of the flexion control apparatus comprises a flexion control element mounted transversely to the longitudinal axis of the boot. The lower edge of the upper rests against the flexion control element. Further, the ends of the flexion control element are integral with the shell base. In this device the flexion control element operates as a cantilevered beam at its two ends during transverse flexion. This arrangement makes it possible to obtain a relatively high initial elastic resistance when the ski boot is slightly flexed but generates a relatively weak elastic resistance when the upper is at maximum flexion by virtue of the operation and configuration of the flexion element.
Thus, there is a need for a ski boot having a flexion control apparatus which is contained in the normal volume of the boot, and which generates a relatively great elastic resistance at the beginning of the flexion of the upper that increases progressively and moderately as the upper continues to flex forwardly.